Generally speaking, a wireless sensor network includes source nodes that are connected to a sink node via a number of parallel routing paths, each path including a number of intermediate nodes. In other words, a wireless sensor network can be characterized as a many-to-one, multi-hop wireless network. The many-to-one aspect of such a network creates a funneling effect that can cause congestion even under light to moderate traffic loads, especially at the sink node.
Data transmission in a wireless video sensor network presents unique challenges beyond those found in other types of wireless sensor networks. First, video streams employ higher bit rates and therefore require greater bandwidths, which aggravate the funneling effect. Second, conventional techniques that utilize data aggregation to mitigate the funneling effect may be impractical in wireless video sensor networks. Aggregation of video data requires sophisticated processing that is generally beyond the capability of the nodes in wireless sensor networks. Even if such processing was practical, a data transmission scheme that proactively mitigates congestion in wireless sensor networks would be valuable.